Utah: Salmonella Infections Linked To Queso Fresco

Public health agencies in Utah, in coordination with the Utah Department of Agriculture and Food, have been investigating a cluster of Salmonella Newport cases in which it appears that the common link is queso fresco, a Mexican-style soft cheese. Officials don’t believe the contaminated cheese is being produced or sold commercially.

Epidemiologic investigations point to queso fresco that is being made in private homes and then either sold to neighbors or given away. A sample of queso fresco produced and distributed by a non-commercial, private source was obtained by Utah Department of Agriculture and Food and tested at the Utah Public Health Laboratory. Salmonella Newport was recovered from the sample.

Public health officials are still uncertain how the cheese is getting contaminated with Salmonella bacteria, but believe the cheese is either being contaminated from ingredients used to make the queso fresco (such as unpasteurized/raw milk), or from cross-contamination of the cheese (e.g. through using a bowl to prepare or hold raw chicken, and then using that same bowl without cleaning it to make the cheese).

Health officials understand that many people enjoy making food from scratch and sharing it with others, especially in these tough economic times. “I am sure that those who make queso fresco in the home and share it with those in the neighborhood don’t intend to make other people sick. It is important that we teach people about proper food handling practices, and that it is against the law to sell privately produced products door-to-door, if they are potentially hazardous,” stated Marilee Poulson, a Foodborne Disease Epidemiologist with the Utah Department of Health.

While this current investigation is focused on individuals infected with Salmonella bacteria, public health officials warn that other dangerous bacteria can also be spread through contaminated queso fresco, such as Listeria, Campylobacter, E. coli, and Brucella. Public health agencies in Utah are currently investigating another cluster of illnesses due to the bacteria Campylobacter which may be associated with contaminated cheese made with raw or unpasteurized milk.

There is no way to detect Salmonella or other bacteria in food without laboratory testing; it cannot be detected by sight, taste, or smell. Salmonella bacteria are commonly transmitted by eating or drinking contaminated food or water. Salmonellosis can also be spread by direct contact with an infected person or animal. Symptoms include: headache, stomach pain, diarrhea, nausea, vomiting and almost always fever; symptoms last between three and seven days.

Making homemade queso fresco can be done safely by following a few simple steps that will help prevent bacterial contamination.

• Use only pasteurized milk to make queso fresco. Queso fresco made from milk that has not been pasteurized can cause severe illness. This is especially dangerous for children, the elderly, and pregnant women. Eating queso fresco made with pasteurized milk will help pregnant women protect themselves and their unborn babies from getting a serious infection.

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• We do not recommend that you use unpasteurized milk to make queso fresco. However, if you choose to do so, it may be less dangerous to use milk from a licensed seller. To obtain a list of licensed sellers of unpasteurized milk, call Utah Department of Agriculture and Food at 801-538-7156.

• Keep milk refrigerated.

• Use proper food handling practices to avoid cross-contamination when making queso fresco, such as: